結果

問題 No.160 最短経路のうち辞書順最小
コンテスト
ユーザー negnat
提出日時 2022-03-01 14:17:10
言語 Rust
(1.83.0 + proconio)
結果
MLE  
実行時間 -
コード長 4,597 bytes
コンパイル時間 10,775 ms
コンパイル使用メモリ 381,672 KB
実行使用メモリ 813,088 KB
最終ジャッジ日時 2024-07-07 20:16:07
合計ジャッジ時間 13,904 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge2
このコードへのチャレンジ
（要ログイン）
ファイルパターン 結果
sample AC * 4
other AC * 1 MLE * 1 -- * 24
権限があれば一括ダウンロードができます
コンパイルメッセージ
warning: unused import: `std::io`
 --> src/main.rs:1:5
  |
1 | use std::io;
  |     ^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused import: `min`
 --> src/main.rs:3:16
  |
3 | use std::cmp::{min, Ordering, Reverse};
  |                ^^^

ソースコード

diff # 

use std::io;
use std::collections::binary_heap::BinaryHeap;
use std::cmp::{min, Ordering, Reverse};

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

#[derive(Debug, Clone, Copy)]
struct Edge {
    to: usize,
    cost: i32,
}

#[derive(Debug, Clone, Copy)]
struct Node {
    id: usize,
    cost: i32,
    prev: Option<usize>,
}

#[derive(Debug)]
struct Graph {
    nodes: Vec<Node>,
    edges: Vec<Vec<Edge>>,
}

impl Graph {
    fn new(n_nodes: usize) -> Self {
        let mut nodes = Vec::with_capacity(n_nodes);
        let edges = vec![Vec::new(); n_nodes];

        for i in 0..n_nodes {
            nodes.push(Node { id: i, cost: i32::MAX, prev: None })
        }

        Self {
            nodes,
            edges,
        }
    }

    fn add_edge(&mut self, from: usize, to: usize, cost: i32) {
        self.edges[from].push(Edge { to, cost });
        self.edges[to].push(Edge { to: from, cost });
    }
}

impl Eq for Node {}

impl PartialEq<Self> for Node {
    fn eq(&self, other: &Self) -> bool {
        self.cost.eq(&other.cost)
    }
}

impl PartialOrd<Self> for Node {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        self.cost.partial_cmp(&other.cost)
    }
}

impl Ord for Node {
    fn cmp(&self, other: &Self) -> Ordering {
        self.cost.cmp(&other.cost)
    }
}

fn dijkstra(graph: &mut Graph, from: usize, to: usize) {
    let mut heap = BinaryHeap::new();
    let mut visited = vec![false; graph.nodes.len()];

    graph.nodes[from].cost = 0;
    heap.push(Reverse(graph.nodes[from]));

    loop {
        if let Some(Reverse(node)) = heap.pop() {
            visited[node.id] = true;

            if node.id == to {
                break;
            }

            for e in &graph.edges[node.id] {
                if visited[e.to] {
                    continue;
                }

                if node.cost + e.cost < graph.nodes[e.to].cost {
                    graph.nodes[e.to].cost = node.cost + e.cost;
                    graph.nodes[e.to].prev = Some(node.id);
                }

                if let Some(prev_node_id) = graph.nodes[e.to].prev {
                    if node.cost + e.cost == graph.nodes[e.to].cost && node.id < prev_node_id {
                        graph.nodes[e.to].prev = Some(node.id);
                    }

                    heap.push(Reverse(graph.nodes[e.to]));
                }
            }
        } else {
            break;
        }
    }
}

fn backtrace_path(graph: &Graph, to: usize) -> Vec<&Node> {
    let mut path = Vec::new();
    let mut node_id = to;

    loop {
        let node = &graph.nodes[node_id];
        path.push(node);

        if let Some(prev_node_id) = node.prev {
            node_id = prev_node_id;
        } else {
            break;
        }
    }

    path.reverse();

    path
}

fn main() {
    input! {
        n: usize,
        m: usize,
        s: usize,
        g: usize,
        edges: [(usize, usize, i32); m]
    }

    let mut graph = Graph::new(n);

    for (from, to, cost) in edges {
        graph.add_edge(from, to, cost);
    }

    dijkstra(&mut graph, s, g);
    let path = backtrace_path(&graph, g);

    let answer = path.iter().map(|p| p.id.to_string()).collect::<Vec<_>>().join(" ");

    println!("{}", answer);
}
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